The invention relates to seat suspensions and swivel assemblies used therewith. More specifically, the present invention relates to a swivel assembly that includes an adjustment plate which controls the rotational movement of the seat by increasing or decreasing tension on a bearing assembly.
In many seat suspensions, a bearing assembly is often disposed between a first swivel plate and a second swivel plate which allows the first plate to rotate with respect to the second plate. To control the ease at which the seat swivels or the rotational movement, a biasing force is often used to urge the plates towards one another. The closer the plates are urged towards one another, the more pressure is exerted on the bearings, and as a result, a greater force is needed to rotate the seat. When the force is decreased, the seat swivels more freely.
However, controlling the biasing force often requires the user to control the distance between the plates and this is often difficult to accomplish because of the manufacturing processes used. It simply is not economically feasible to manufacture all of the parts involved in a swivel assembly within the manufacturing tolerances needed to maintain a set distance between the plates. To compensate for this, current practice is to use spacers, shims, and the like to control the distance between the plates, and consequently, the pressure on the bearings. The drawback in using this type of system is that the installation is labor intensive, precision is often difficult to achieve, and subsequent adjustments require new shims, spacers, and the like.
The present invention solves the above noted problems by using an adjustment plate that adjustably controls the pressure exerted on the bearings. The adjustment plate rests upon the first swivel plate and is connected to the second swivel plate by fasteners. A plurality of sloped surfaces having slots through which the fasteners pass permits the adjustment plate to rotate about the fasteners. As the plate is rotated in a direction which causes the fastener heads to engage the portion of the sloped surface which increases in height, the first swivel plate is urged towards the second swivel plate thereby increasing the pressure exerted on the bearing assembly which increases the resistance to rotational movement. Conversely, when the adjustment plate is rotated in the opposite direction towards the area of decreasing height, the resistance to rotational decreases since the distance between the plates increases.